1. Field of the Invention
The present invention relates to a method for producing carbon nanotubes (CNTs). Especially, the present invention relates to a method performing in-situ thermal decomposition of polymers to produce carbon nanotubes.
2. The Prior Arts
Nanotechnology is one of the most important top technologies in this century, which is also a science technology evoked by new industrial revolution. This emerging technique is attractive at present and is gradually displayed in an attitude of changing the basic research fields of information technology, biological science, environmental science, energy source, material science and so on. The trend of industrial elements toward small features, high density, fast transmission, low energy cost and high production rate results in the further needs of element materials. Therefore, nanomaterial containing nanostructure becomes the best material to fulfill the abovementioned needs. Recently, nanomaterials gradually become arresting, one of the most bodacious, being broadly discussed and applied material is carbon nanotubes.
Since their discovery in nineties, carbon nanotubes have been attracting much attention due to their special cylinder like structure constructed of hexagonal array, as well as the unique electrical, magnetic, optic characteristics and the potential applications. The fields of carbon nanotube applications include photo-electric elements, electric elements, biomedical science, energy materials, and artificial diamonds, etcetera. International technology and industry are all emphasized on this technology without regard to countries or research fields, such as IBM Company and NASA in USA, NEC and Shawa Denko Companies in Japan, and Max-Planck Institute in Germany are focused very broadly and deeply in the field of carbon nanotubes and their applications. The reports on new research of carbon nanotubes are competing internationally.
On the other hand, due to high aspect ratio and small tip radii of curvature, carbon nanotubes are very suitable for electron field emission. Carbon nanotube materials are alternatives to conventional metallic microtips in field emission display (FED) application for high luminance and efficiency. In the application of recording media, carbon nanotubes can be used in recording head with memory of terabyte scale (1 Terabyte=1,000 Gegabytes). Moreover, carbon nanotubes are the basic materials of other nanostructures, such as the synthesizing templates of nanowire and nanorod.
The existing production methods of carbon nanotubes include arc discharge, chemical vapor deposition (CVD), pulsed laser deposition, plasma enhanced CVD, microwave plasma CVD and laser ablation and so on, among which arc discharge and chemical vapor deposition are commonly used. These two methods need high temperatures (typically more than 1000° C.), high production cost, and the starting procedures and process procedures are more complex and with higher risk. Accordingly, it is desirable to develop an improved method of producing carbon nanotubes with which the process can be operated easily and performed at low working temperature and has high safety to eliminate above-mentioned problems in the prior arts.